Humanin is a small peptide with an unusual origin story: it was found by screening for a gene that kept cultured neurons alive, and it was later grouped with other peptides encoded in mitochondrial DNA. This profile summarizes what the published literature reports and what a lab should keep in mind when reading it.
What Humanin Is
Humanin (HN) is a 24-residue peptide. In the 2003 paper by Ikonen and colleagues it is described as a 24-amino-acid peptide, and an alanine substitution at its sixth residue (phenylalanine) was used to show which part of the peptide mattered for an interaction.
| Property | Value |
|---|---|
| Length | 24 residues |
| Sequence (UniProt Q8IVG9) | MAPRGFSCLLLLTSEIDLPVKRRA |
| Origin | Gene identified by cDNA expression screening |
| Encoded in | Mitochondrial DNA (small open reading frame) |
| Relatives | Other mitochondria-derived peptides, including MOTS-c |
How Humanin Entered the Literature
In 2001, Hashimoto and colleagues used a functional expression screening approach to look for a gene whose product prevented cell death in cultured neurons exposed to genes and a protein fragment associated with familial Alzheimer's disease. They named the gene humanin and reported that the encoded polypeptide was secreted into the culture medium and that its activity depended on its primary structure. A correction to that paper was published later in 2001, so cite the corrected version.
In 2003, Ikonen and colleagues identified insulin-like growth factor-binding protein 3 (IGFBP-3) as a binding partner of humanin by a yeast two-hybrid screen and followed up with pull-down and co-immunoprecipitation experiments. Their reported interaction depended on the phenylalanine at position 6.
In 2022, Miller and colleagues reviewed the field of mitochondria-derived peptides (MDPs): small open reading frames in circular mitochondrial DNA can encode microproteins, and at the time of the review eight had been published, namely humanin, MOTS-c and SHLP1 to SHLP6. That review is useful as a map, but its conflict-of-interest statement discloses that one author is an inventor on intellectual property licensed to a company working on these peptides. See also our profile of MOTS-c.
What Cell Studies Have Examined
- Secretion and structure dependence. The 2001 paper reported that cells secreted the peptide and that a changed sequence lost activity.
- Protein binding. The 2003 paper reported high-affinity, specific binding to IGFBP-3 and context-dependent outcomes depending on the cell type used.
- Cell-type dependence. The same paper found that humanin blocked an IGFBP-3 effect in one cell line but not in two others, which is a reminder that results from one cell line should not be generalized.
These are cell culture studies. They describe what was observed in a dish, and they are not evidence of any effect in people.
Reading the Humanin Literature Carefully
- Name versus analog. Some papers use analogs with a changed residue, such as the F6A mutant in the 2003 study. Check which exact sequence each paper used before comparing results.
- Gene versus peptide. The 2001 discovery came from expressing a cDNA in cells. A study that expresses a gene is not the same experiment as one that adds a synthetic peptide to a dish.
- Corrections. Check for errata, as the 2001 paper has one. Our guide on checking whether a paper is still standing explains how.
If You Source This Compound for Research
- Ask for an analytical report that matches the lot number.
- Compare the observed mass with the exact sequence you intend to study, including any substitution.
- Check HPLC purity, since 24-residue peptides with hydrophobic stretches can be hard to purify cleanly.
- Store lyophilized material cold, dry and away from light. See Storing Lyophilized Peptides in the Lab and How to Read a Peptide Analytical Report.
FAQ
Why is it called a mitochondria-derived peptide? Because its coding sequence sits in mitochondrial DNA, as described in the 2022 review.
Is humanin the same as MOTS-c? No. Both are encoded in mitochondrial DNA, but they are different peptides of different lengths and sequences.
Why do two papers using "humanin" sometimes disagree? Often because they used different sequences, cell lines or delivery methods. Always compare the methods section first.
Sources
- Hashimoto Y et al. Proceedings of the National Academy of Sciences, 2001. PubMed 11371646: https://pubmed.ncbi.nlm.nih.gov/11371646/
- Ikonen M et al. Proceedings of the National Academy of Sciences, 2003. PubMed 14561895: https://pubmed.ncbi.nlm.nih.gov/14561895/
- Miller B et al. Journal of Clinical Investigation, 2022. PubMed 35499074: https://pubmed.ncbi.nlm.nih.gov/35499074/
- UniProt entry Q8IVG9 (humanin sequence): https://www.uniprot.org/uniprotkb/Q8IVG9
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